The term cascading refers to your ability to apply multiple styles to the 

same element or web page. For example, you can create one CSS rule to 

apply color and another rule to apply margins, and apply them both to the 

same text on a page. The defined styles  cascade  to the elements on your 

web page, ultimately creating the design you want.

A major advantage of CSS is that it can be updated easily; when you 

update a CSS rule in one place, the formatting of all of the documents that 

use the defined style are automatically updated to the new style.

You can define the following types of rules in Dreamweaver:

I

Custom CSS rules, also called class styles, let you apply style attributes 

to any range or block of text. All class styles begin with a period (.). For 

example, you could create a class style called .red, set the 

color

property of the rule to red, and apply the style to a portion of already 

styled paragraph text.

I

HTML tag rules redefine the formatting for a particular tag, such as 

p

or 

h1

. When you create or change a CSS rule for the 

h1

 tag, all text 

formatted with the 

h1

 tag is immediately updated.

I

CSS selector rules (advanced styles) redefine the formatting for a 

particular combination of elements, or for other selector forms as 

allowed by CSS (for example, the selector 

td h2

 applies whenever an 

h2

 header appears inside a table cell.) Advanced styles can also redefine 

the formatting for tags that contain a specific 

id

 attribute (for example, 

the styles defined by 

#myStyle

 apply to all tags that contain the 

attribute value pair 

id="myStyle"

).

For more information, see  About text formatting in Dreamweaver  in 

Using Dreamweaver.

Learn about CSS 103